list would then have to be checked against military records to see if a particular set of twins did, in fact, enlist. This method was cheaper than beginning with the military records and then checking to see if two servicemembers with the same last name were actually twins. To perform experiments that tried to discriminate between the effects of environment and heredity, it would also be necessary to separate the sample into monozygotic and dizygotic pairs (fraternal and identical twins). Jablon believed that, by using physical characteristics such as eye color, hair color, height, weight, and complexion, as well as fingerprints (obtained from the Federal Bureau of Investigation [FBI]), he could make accurate classifications in 80 percent of the cases.74 The committee expressed enthusiasm for the project, provided that a source of funds could be found.
The Follow-up Agency sought external advice from Dr. James Neel of the University of Michigan's Institute of Human Biology, who advised Bernard Cohen that, in an ideal situation, one would like to be able to observe the twins from birth to the grave. A sample of twins from Veterans Administration records would eliminate the first and much of the second decade of life and would not contain many people with congenital defects who, presumably, would have been screened out in the induction process. Hence, the sample would not be of much use in studying congenital malformations or the malignant diseases of childhood such as leukemia. Yet Neel believed the sample "would certainly be far better than anything that the world has ever had before."75
Beginning in 1957, Neel chaired an ad hoc committee on studies of veteran twins that gave the NRC and the Follow-up Agency still more advice on the project. It became a permanent institution in the Follow-up Agency and continued the ongoing separation of the agency and the Committee on Veterans Medical Problems by removing much of the twin study oversight from the committee. At the first meeting, after a lengthy discussion of such technical matters as determining zygosity (i.e., whether the twins were identical or fraternal), the ad hoc committee reached the same positive conclusion as the CVMP. It recommended that "steps be taken to establish a roster of twin veterans as soon as possible." As soon as the roster was established, the committee suggested that the agency undertake a pilot study to compare the relative effectiveness of various diagnostic methods for establishing zygosity.76
Although the study of twins appeared to set the Follow-up Agency off in a new direction, Gilbert Beebe hesitated to loosen the ties with the Committee on Veterans Medical Problems. His staff, he realized, focused on methodology, not specific medical subjects. Stimulus for selecting specific subjects had to come from external investigators, and the agency needed the committee's help in making connections with such researchers. The agency, Beebe noted, had ready access to records, not to investigators.
In 1957, another important development occurred when Keith Cannan asked the agency to participate in the program of the Atomic Bomb Casualty Commission (ABCC; Box 5). Seymour Jablon became the first staff member to go to